Three problems related to wiring have been reported for the 2005 GMC Envoy. The most recently reported issues are listed below.
I have a 2005 GMC Envoy and I have had to replace a water pump, a blower motor wiring harness that melted into my truck, the lights are half out on me heater and my door panel where you put the windows up and down, the winshield wiper in the back works when it wants my speed ometer is stuck on 40 even when its off and my check engine light is on and I bought this truck less than 2 years ago!.
Speedometer jumps from 120 to wherever. Can never tell how fast or slow I'm going. Never displays correct speed. Oil pressure gage goes up and down. Also, headlughts keep going out. Had to take to mechanic to redo wiring for both headlights.
One day my oil gauge stopped working. A few months later the speedometer stopped working and eventually every gauge in my panel stopped working. This all started around Nov of 2008. I could not figure out what was going on. I checked all fuses, bulbs and wiring. Now two days ago my head lights stoped working on low beam. Nothing was found to be the problem. I recently found hundreds of Envoy owners with the exact same issues and now know it is the instrument cluster panel. Est cost for the part only $570.